The present invention relates to a self-aligned silicide process for use in a self-aligned double polysilicon process as a means of improving the performance of bipolar transistors.
Current bipolar technology is capable of fabricating transistors with dimensions below about 5 microns from one side to the other. Such reduced dimensions translate into high speed provided the effects of parasitic resistances and capacitances can be minimized. By using trench isolation in combination with a double polysilicon process, greatly reduced base resistance, collector-base capacitance, and collector-substrate capacitance can be achieved. One limiting factor to achieving further reductions in factors such as base resistance is the contact resistance in the polysilicon that is used to contact the base and emitter.
Accordingly, it is an object of the invention to provide a process for improving the double polysilicon process as used on bipolar transistors. It is a further object of the invention to provide a process that lowers the polysilicon contact resistance and thereby enhances transistor performance.